Went to their Christmas performance here in Las Vegas some years ago. Have always loved hearing their classics such as "Wizards in Winter" on the radio. Wife and I thought "what better way to celebrate the holiday season" than to see them live in concert. Wow. What a mistake we made.
First of all, their performance is LONG. The first half, had we made it through, was about 90 minutes, and tells a "Christmas story" complete with characters portraying a seasonal tale about hope and joy. Only it was absolutely HORRIBLE and our only hope and joy was to leave the concert about one hour into it. (Side note: My wife and I are musicians; we know what quality in a live performance is). As others have noted, the performers are reminiscent of a bad 80s hair band, the light effects are painful because the spots often point directly into the audiences' eyes, and volume is WAY too loud, and the performers HORRIBLE singers.
We were among literally HUNDREDS of audience members who walked out during the first half; we found out later that they only perform their classics on the second half, after the intermission. Nothing could have made us stay that long.
We also learned, at a later date, that TSO has two travelling shows that perform simultaneously in different parts of the country. I concede it's possible that we saw the "B" band, but regardless, this was a learning experience for us; we learned not to see them in a live performance!
I do have many friends who love their live show, so they do have an appeal to certain people. We are not among that group.